The inventive concept relates generally to electronic memory technologies. More particularly, certain embodiments of the inventive concept relate to semiconductor memory devices having an adjustable refresh period.
Certain types of memory devices require refresh operations to retain stored data. An example of such a memory device is a dynamic random access memory (DRAM), which stores data by maintaining charges in a capacitor. The charges tend to leak over time, so refresh operations are performed to compensate for this leakage. The refresh operation is typically performed on a periodic basis, with the period determined by the expected rate of charge leakage.
In some contexts, the rate of charge leakage may vary significantly between different memory cells, with so-called “weak cells” requiring more frequent refreshing due to a higher rate of leakage. In these contexts, if the refresh period is too long, the weak cells may lose stored data. On the other hand, if the refresh period is shorter, power consumption will be higher. Accordingly, there is a general tradeoff between the reliability of weak cells and overall power consumption in a DRAM.